The field of the invention generally pertains to push buttons, and more particularly to a weatherproof and vandalproof pedestrian push button assembly for generating a signal at a street crosswalk.
Various types of push button assemblies have been developed and used as a call or signal generator in various electronic devices and systems. Pedestrian push button assemblies and systems, in particular, are widely used at street corners and intersections for assisting pedestrians when crossing a street. While providing a beneficial service to pedestrians, they often become the target of vandalism and abuse, which can diminish the capacity of such systems to operate effectively. It is not uncommon for pedestrian push buttons to be struck with hard objects, such as baseball bats, hockey sticks, skateboards and hammers. Additionally, they are often repeatedly struck by hand in the belief that such actions would speed up the changing of the lights. In other cases, adhesives, such as Super Glue and gum, are used to stick or jam the button mechanism to prevent its operation. Moreover, because pedestrian push buttons are used outside, they are exposed and susceptible to harsh weather and other environmental conditions, such as rain and snow.
It is also known for many push button systems to utilize force-sensitive piezoelectric elements which produce a voltage pulse upon being acted upon by a mechanical pressure. The use of piezoelectric crystals and materials are especially useful in the construction of solid state switches requiring little or no actuating movement or travel. Because such push buttons have little or no contacting parts, such assemblies are useful for a high number of operation cycles with little or no wear.
It In U.S. Pat. No. 5,477,942, an electric push button assembly for elevators is shown having a plunger element with a plug-shaped extension covered with an elastic pressure cap. The elastic pressure cap is positioned adjacent a force-sensitive resister and upon actuation of the plunger element, the elastic pressure cap applies a mechanical pressure against the force-sensitive resister. The plunger element is permanently biased away from the force-sensitive resister by means of a compression spring.
Additionally, in U.S. Pat. No. 5,587,567, a push button panel is shown for use with elevators having a front panel with push button areas on a front surface of the front panel, and elements sensitive to pressure changes positioned behind the front panel. The front panel is made of a material having a high degree of rigidity, such that applying pressure to the front panel induces a signal to be generated by means of the pressure sensitive elements.
While both the ""567 and ""942 patents disclose push button assemblies utilizing a force-sensitive resister, i.e. piezoelectric element, they are not particularly suitable for outdoor use where they are subject to environmental exposure and conditions. For example, the electronic push button assembly in the ""942 patent utilizes a compression spring to resiliently actuate the plunger element. The compression spring, however, is not designed to weatherproof the pushbutton, by sealing or otherwise preventing external elements from reaching the inside. Additionally, because the ""567 patent has the pressure sensitive elements positioned directly behind the thin-sheet front panel, they are especially vulnerable to acts of vandalism involving high impact.
Thus, it would be beneficial to have a weatherproof push button assembly designed to withstand the ever-changing and harsh environmental conditions, as well as being essentially impervious and resistant to acts of vandalism.
It is an object of the present invention to provide a weatherproof pedestrian push button assembly for outdoor use, which activates a signal generating device to generate a signal at a street crosswalk.
It is a further object of the present invention to provide a pedestrian push button assembly which is highly impact resistant and resistant to violent acts of vandalism.
It is a still further object of the present invention to provide a push button assembly having a minimal number of moving parts which approximate a solid body when actuated, and having visual and audible notification of signal activation.
The present invention is for a push button assembly for activating signal-generating means to generate a signal at a street crosswalk. In a preferred embodiment, the pedestrian push button assembly comprises a rigid frame having opposing inner and outer frame ends. The outer frame end has a central aperture, a stopper surface located ulterior to the central aperture, and a perimetric groove surrounding the central aperture. The push button assembly also comprises a resiliently-biasing sealing element which is adapted to be seated in a perimetric groove surrounding the central aperture. Furthermore, a piezoelectric element is positioned across the central aperture and electrically connected to the signal-generating means. The piezoelectric element activates the signal-generating means to generate the signal when mechanical pressure is acted thereupon.
The mechanical pressure is supplied by a button portion secured to the rigid frame. The button portion has opposing inner and outer button ends with the inner button end having a resiliently-biasing pressure element mounted thereon. The inner button end also has an abutment surface located ulterior to the resiliently-biasing pressure element, as well as a seal-contact portion surrounding the resiliently-biasing pressure element. The inner button end is adapted to be secured to the outer frame end such that the seal-contact portion sealably contacts the resiliently-biasing sealing element in an unbiased state, the abutment surface confronts the stopper surface, and the resiliently-biasing pressure element contacts the piezoelectric element.
In this manner, upon a pressure being applied against the outer button end, the seal contact portion resiliently-biases the resiliently-biasing sealing element, and the resiliently-biasing pressure element is urged to apply a mechanical pressure against the piezoelectric element. Because the movement is of an incremental magnitude, a user may not perceive button movement. As a result, the piezoelectric element activates the signal generating means to generate the signal.